Review time for independents is longer than it is for exclusives, and can be a week or two when things are moving slowly. If the queue is in good shape it can be just a few days. In general, sales will take a while longer to build on iStock, but a lot depends on your image and the niche in which it's competing. Also there are periods when the best match (best match) sort order favors newer or older images and that can have a huge effect on sales, temporarily.